Bovine-associated mucoprotein: de novo synthesis by nonmammary tissues

Bovine tissues were cultured in vitro in the presence of carbon-14 amino acids and tritiated hexosamine to examine the de novo synthesis of the milk fat globule glycoprotein bovine-associated mucoprotein, by selected tissues. Among tissues examined, the relative synthesis of bovine-associated mucoprotein was highest in mammary tissue. The de novo synthesized bovine-associated mucoprotein in mammary and lacrimal gland cultures when examined for incorporation of carbon-14, had similar sedimentation profiles in sucrose density gradients and incorporated the same relative amount of carbohydrate. The bovine-associated mucoprotein synthesized by lung and spleen cultures sedimented in similar fashion to mammary gland bovine-associated mucoprotein when incorporation of carbon-14 was used as the marker, but it displayed greater heterogeneity when evaluated for tritium incorporation. Bovine-associated mucoprotein in the lung and spleen incorporated relatively less carbohydrate than that synthesized by mammary tissue. These findings support the concept of intertissue heterogeneity, which had been suggested by previous studies.